Mariam Araujo, 25, plays with Lucas, her 4-months old second child and born with microcephaly as they wait for a physiotherapy session in Pedro I hospital in Campina Grande, Brazil, on February 17, 2016. Photo: Reuters/Ricardo Moraes

The number of confirmed and suspected cases of microcephaly in Brazil associated with the Zika virus has risen to 4,690 from 4,443 a week earlier, the Ministry of Health said on Tuesday.

Zika, which is spread by mosquitos, has been linked to microcephaly -- a birth defect in which the infant is born with an abnormally small head. AFP/Marvin Recinos

Of these, the number of confirmed cases climbed to 583 from 508 a week earlier, while suspected ones increased to 4,107 from 3,935 in the same period.

Jackeline, 26, holds her son who is 4-months old and born with microcephaly, in front of their house in Olinda, near Recife, Brazil, February 11, 2016. Recent laboratory analyses identified Zika virus infections in three people who died in Brazil last year, the health ministry said on Thursday, although authorities could not confirm that Zika alone was responsible for their deaths. REUTERS/Nacho Doce

Brazil considered most of the cases of babies born with abnormally small heads to be related to Zika, though the link between the virus and the birth defects has not been scientifically established.